put the city in gridlock. it's part of a billion dollar highway improvement project. >>> 2,000 bicycle riders from all over the world are expected to be in san francisco tonight. it's for the 20th anniversary of the critical mass movement. now the big bike ride take place on the last day of the month. critical mass riders say the popularity of bike riding has grown in the last 20 years. >> it seemed to become more fashionable. definitely for me, i find the easiest way to get around town. i always know how long it's going to take me to get somewhere, which is if you're riding a car or transit, you don't know how long you need to plan in advance for a delay of sorts. >> so here's a heads up. critical mass kicks off at 6:00 tonight. yeah, expect delays. dozens of really smart people are competing in facebook's hack-a-thon. they're creating websites to help high school students get into and succeed in college. organizers are interested in helping low income students with their college plans. 30 grants will be hand